Metapopulation Dynamics of Gopher Frogs (Rana capito) in Georgia

Eva Kerr

University of Georgia and the Jones Center at Ichauway

November 2025

Background

Landscapes are – by definition – heterogeneous, composed of patches of habitat embedded within a surrounding “matrix” of non-habitat. Alterations to the landscape through habitat loss and degradation lead to the breakdown of important processes that determine population resilience on a landscape. When restoring landscapes that have been altered, managing habitat patches is typically the initial action used to increase species persistence. To restore habitat patches, managers need to understand what habitat conditions support species occupancy. 

However, just restoring habitat patches ignores the importance of movement between patches, referred to as functional connectivity, that facilitates demographic and genetic rescue. Thus, to restore movement between patches managers requires knowledge of which landscape features facilitate or act as barriers to connectivity. Landscape genetics provides a framework for understanding functional connectivity by revealing patterns of gene flow in relation to landscape composition and structure. Understanding functional connectivity of rare or threatened species can identify actions such as the best locations for restoration to improve connectivity.

Gopher Frogs are a high priority species and considered a Species of Greatest Conservation Need in all states within their range. Very little is known about what landscape features impact Gopher Frog movement. There are only two sites in Georgia with Gopher Frogs that are logistically feasible to study functional connectivity. Both sites have extensive areas of managed open, pine forest habitats with abundant terrestrial refugia and a high density of wetlands suitable for Gopher Frog breeding.

Figure 1. A Gopher Frog on an apron of a Tortoise Burrow captured using a funnel trap. Photo by Ben Thesing.

Methods

We collected genetic samples when an observer found any Gopher Frog egg mass, tadpole, juvenile, or adult during surveys from January to September 2024. We employed multiple capture methods as Gopher Frogs are a rare and cryptic species. At both sites, we conducted monthly dipnet surveys and scoped Gopher Tortoise burrows using funnel traps to capture Gopher Frogs. We also conducted bi-weekly egg mass surveys at one site. When individuals or egg masses were encountered, we collected 5–10 eggs, adult toe clips, or tadpole tail clips, and preserved all samples in 95% ethanol. We extracted the DNA and genotyped samples at 10 microsatellite loci. We then used this data to (1) evaluate Gopher Frog genetic structure within the two landscapes, (2) estimate genetic diversity, and (3) identify landscape features that act as barriers to connectivity among Gopher Frog breeding sites.

Figure 2. A Gopher Frog tadpole captured during dipnet surveys. Photo by Jade Samples.

Early Findings

At Site A, we detected Gopher Frogs at 10 of the 13 wetlands surveyed and three terrestrial locations. At Site B, we detected them at only 3 of the 14 wetlands; however, we had 49 terrestrial detections. We found evidence of low genetic diversity on both sites. In addition, we found that larger landscape features such as a large creek and a highway are impeding connectivity among Gopher Frog breeding wetlands on Site A, but connectivity still appears to be fairly high (Fig. 3). In contrast, we found clear evidence of genetic spatial structuring and limited functional connectivity among Gopher Frog breeding wetlands across Site B (Fig. 3). We again found evidence that large landscape features (e.g., salt marsh and tidally inundated wetlands) likely restrict connectivity.

Figure 3. Genetic structure of Gopher Frogs at Site A and Site B. Each pie represents an individual frog, with colors showing the proportion of different genetic populations. Pies are placed roughly where frogs were found in the landscape. Both sites have spatial structuring though connectivity appears higher on Site A.

We also found evidence that degraded wetland conditions (i.e., closed canopies) on Site B are restricting occupancy and functional connectivity on the landscape. Wetland degradation can limit recruitment from breeding wetlands and increasing the distance between suitable wetlands. We believe that the differences in wetland occupancy and connectivity between the two landscapes are the result of differences in land use and management history. When compared to Site B, Site A had more open-canopy wetlands, which are conditions often associated with Gopher Frog breeding wetlands (Fig. 4). We believe this reflects Site A’s longer history of wetland vegetation management and highlights the need for targeted canopy removal and vegetation management of wetlands on Site B [and other landscapes]. Low Gopher Frog genetic diversity in both landscapes suggests the potential for broader drivers of genetic diversity loss among Gopher Frog populations. Collectively, our results suggest that two of the most robust Gopher Frog populations in Georgia both show reasons to be concerned about their long-term resilience.

Figure 4. Bar lengths represent percent canopy cover, and colors correspond to predicted wetland occupancy probability of Gopher Frogs for Site A and B. There is a clear trend of increasing wetland occupancy with decreasing canopy cover. Site B has lower occupancy and a higher number of more closed canopy wetlands.